Weather Eye with John Maunder

The 'Maunder Minimum” period is named after the solar astronomer Edward Walter Maunder (1851-1928), who while working at The Royal Observatory at Greenwich discovered the dearth of sunspots during the 1650-1700 period.

During one 30-year period within the Maunder Minimum, there were only about 50 sunspots compared with a more typical 40,000. This period coincided with an extremely cold period in Europe. Maunder was a driving force in the foundation of the British Astronomical Association, and was a Fellow of the Royal Astronomical Society.

Throughout the solar cycle, which is usually about 11 years in length, the latitude of sunspot occurrences varies with an interesting pattern. The chart shows the latitude of sunspot occurrence versus time, in years.

The current prediction for Sunspot Cycle 24 gives a smoothed sunspot number maximum of about 72 in late 2013. The smoothed sunspot number reached a peak of 81.9 in April 2014. We are currently over six years into Cycle 24. The current predicted and observed size makes this the smallest sunspot cycle since Cycle 14 which had a maximum of 64.2 in February of 1906.

Sunspots are typically confined to an equatorial belt, on the sun, between 35 degrees south and 35 degrees north latitude. At the beginning of a new solar cycle, sunspots tend to form at high latitudes, but as the cycle reaches a maximum – that is a large numbers of sunspots,the spots form at lower latitudes. Near the minimum of the cycle, sunspots appear even closer to the equator. And as a new cycle starts again, sunspots again appear at high latitudes. This recurrent behaviour of sunspots gives rise to the ‘Maunder Butterfly' pattern as shown in the chart from Nasa.

Time will tell whether the sun will once again go into another Maunder Minimum within the lifetime of the present generation, and what affect it will have on our climate.

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